In this paper we propose a particle swarm optimization based approach for designing CMOS low noise amplifier (LNA). Existence of tradeoffs between noise, gain, linearity, stability and power consumption in LNA design, forces the designer to accomplish such a long time complicated work to optimize the circuit. So the utilization of a modern optimization is inevitable. In this work the usage of PSO algorithm in LNA circuit design optimization has been investigated. The performance of LNA circuit is evaluated through HSPICE and PSO algorithm is implemented in MATLAB, so a combination of MATLAB and HSPICE is performed. A cascode LNA is designed using 0.18?m CMOS technology foe near 2.4 GHz band applications. The results of this work indicate the effectiveness of this optimization approach that is a time saver method.